A. We are studying chromosomal translocation and onc genes in Burkitt's lymphoma. We have cloned and sequenced the t(8:14) chromosome translocation from a Burkitt's lymphoma cell line (ref. 1). This line contains a translocated and rearranged myc onc gene. We have now directed our attention to a Burkitt's lymphoma cell line with a t(8:22) translocation wherein myc is neither rearranged, translocated, nor activated. We are characterizing the structure of the translocation in this line and investigating the possible involvement of other onc genes. B. Human cytomegalovirus (HCMV) is highly associated with AIDS and Kaposi's sarcoma. We have been studying nucleic acid homology between the myc onc gene and genomic fragment of HCMV that is able to transform cells in culture after DNA-mediated gene transfer. We are also characterizing Kaposi's cell lines and tissue for the expression of this transforming viral genomic fragment. C. The estrogen-responsive MCF-7 human breast cancer cell line has been shown experimentally to alter its growth performance and malignant potential in response to exogenous hormonal stimulation. It also appears that in response to estrogen stimulation these cells secrete a number of growth promoting proteins. We are in the process of cloning mRNA sequences expressed in response to estrogen stimulation of MCF-7 cells.